1. Field of the Invention
The present invention relates to a welder's eyeshield, more particularly to a welder's eyeshield with an optical filter for attenuating infrared and ultraviolet light.
2. Description of the Related Art
An eyeshield mask is generally used for protecting the wearer's eyes from extremely bright light such as light emitted during welding or the like. Traditional eyeshield masks include a headpiece for covering the wearer's face, and a lens window disposed on a center portion of the headpiece. A dark-colored lens filter having low light transmissivity is mounted on the lens window for protecting the wearer's eyes from direct exposure to harmful light. However, because the light transmissivity of the lens filter employed in the conventional eyeshield mask is relatively low and fixed, the conventional eyeshield mask can only be used under bright ambient light conditions. When the ambient light is weak, the wearer normally has to remove the mask so as not to impair his seeing ability. In this case, the need to put on and take off the mask frequently during welding inconveniences the wearer.
U.S. Pat. No. 4,155,122 disclosed an eyeshield (see FIGS. 1 and 2) having a helmet 1 with a window 10 provided thereon. A liquid crystal assembly 11 and an optical filter lens 12 are juxtaposed on the window 10. The light transmissivity of the liquid crystal assembly 11 can be adjusted by a control circuit 13 connected to the liquid crystal assembly 11, thereby allowing this type of eyeshield to overcome the disadvantage described above. However, manufacturing of this type of eyeshield is laborious and incurs a higher rate of defects. This is due to the fact that the substrate used for the optical filter lens 12 is made of glass, which is fragile and tends to break during processing. Moreover, the surface of the glass is coated with a layer of reflective film 14 by vacuum electro-plating. The reflective film 14, which is merely adhered on the surface of the glass substrate, tends to be scratched off, thereby resulting in the loss of its effect on filtering light. In addition, the film 14 tends to be influenced by the ambient environment, such as temperature or moisture that is conducive to mold growth which can also cause the film 14 to lose its effect on filtering light too.